linux-kernel - Re: VT_PROCESS, VT_LOCKSWITCH capabilities

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Date:	Wed, 01 Aug 2007 04:44:32 +0200
From:	Frank Benkstein <frank@...kstein.net>
To:	linux-kernel@...r.kernel.org
Subject: Re: VT_PROCESS, VT_LOCKSWITCH capabilities

Frank Benkstein wrote:
> I wonder why there are different permissions needed for VT_PROCESS
> (access to the current virtual console) and VT_LOCKSWITCH
> (CAP_SYS_TTY_CONFIG).

To be more direct:

require CAP_SYS_TTY_CONFIG for VT_SETMODE as its essentially the same as
VT_LOCKSWITCH and said capability is already required there

diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index c6f6f42..7034a68 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -662,7 +662,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
        {
                struct vt_mode tmp;

-               if (!perm)
+               if (!perm || !capable(CAP_SYS_TTY_CONFIG))
                        return -EPERM;
                if (copy_from_user(&tmp, up, sizeof(struct vt_mode)))
                        return -EFAULT;

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